XRN2 and HIV-1 infection: In addition, TAF4, a transcriptional cofactor of SETX, has also been found to reduce transcription activation by premature transcription termination [59,65]; similarly, SETX, XRN2, and RRP6/EXOSC10 are believed to act as cooperative genes to force premature termination of RNA transcription in HIV-1 infection [66,67] (Figure S1).